This invention relates to novel crosslinkable fluorene compounds and methods for their preparation. The invention further relates to oligomers and polymers of such compounds, including crosslinked derivatives thereof, as well as films and coatings prepared from such compounds, oligomers or polymers, processes for preparing such films and coatings, and electronic devices, especially electroluminescent devices, comprised of one or more layers of such polymer films.
U.S. Pat. Nos. 6,605,373, 6,362,310, 6,255,449, 6,255,447, 6,169,163, 5,962,631 and related patents disclosed certain crosslinkable substituted fluorene compounds and oligomers and polymers therefrom. Macromolecular Rapid Communication 21, 583-589 (2000) described the synthesis of arylamine containing crosslinkable hole transport materials containing a crosslinkable oxetane group. Macromolecular Rapid Communication 20, 224-228 (1999) described the synthesis of triarylamine small molecules with crosslinkable oxetane groups that can be spin-coated and crosslinked as films. The foregoing references, to the extent crosslinked polymers are disclosed, lack a conjugated polymer backbone, and have only restricted charge transport ability.
In WO 2004/072123 fluorendiyl containing compounds are disclosed for use in organic light-emitting displays. Related compounds are also disclosed in U.S. Pat. No. 6,559,256 and USA 2004/0054152, published Mar. 18, 2004.
Recent advances in display technology have resulted in improved compounds and fabrication techniques for electroluminescent devices such as light-emitting diodes (LED's). High luminance materials are now available for a large portion of the visible light spectrum, including blue light emitting compounds. Recently it has been discovered that improved lifetimes and efficiencies of the active or light emitting layer of a multilayer LED can be obtained by incorporation of a charge transport layer into a multilayer LED between the active or light emitting layer and the anode. Such layers may also be referred to as a hole injection and/or hole transport layer where the purpose is to improve hole injection into the light emitting layer and to provide a buffer layer between the anode and the light emitting layer. In other applications, such an inter-layer between the hole transport layer and light emitting layer has been shown to provide improved device efficiency and lifetime.
The present invention is directed to novel compounds for use in hole transport layers and interlayers of a multilayer LED, as well as in other electronic devices such as field effect transistors (FET's), photovoltaic cells, and even for integrated circuits or printed circuit boards.